Bearing composition



Re. 26,088 Reissued Sept. 20, 1966 26 B88 BEARING c'oMPosmoN Robert RlllOD-Millel' and Saul Ricklln, Bristol, R.l., as-

signors to Dixon Corporation, a corporation of Rhode Island No Drawing. Original No. 3,122,505 dated Feb. 25, 1964, Ser. No. 102,104, Apr. 11, 1661. Application for reissue Feb. 24, 1965, Ser. No. 452,039

46 Claims. (Cl. 252-12 Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This application is a continuation-impart of our applications, Serial No. 775,713, filed November 24, 1958, which was a continuation of our application Serial No. 573,633, filed March 26, 1956, which was a continuation of our application Serial No. 478,500, filed December 29, 1954, all applications being now abandoned.

This invention relates to a composition of matter of the type more particularly useful for sliding surfaces such as a bearing where a considerable pressure is applied through the bearing, an instance of which would be a bearing for the top roll of a spinning frame, which top roll is weighted.

Bearings of this character were originally formed of metal. It is desired that there be no lubricant used for certain bearings, such as are used for the top roll of a spinning frame, as the textile material upon which the roll operates may become stained or damaged by such lubricant, and accordingly some materials other than metai have been attempted. We are familiar with the use of Teflon, which is polytetrafluoroethylene, a material which is the subject of U8. Patent No. 2,230,654, dated February 4, 1941. We have found that this material has poor wear resistance and is unsuitable for use as a bearing where considerable weights are applied. We are also familiar with the use of Teflon in which there has been mixed particles of a silicate such as mica, talc, aluminum silicate or glass, which is the subject matter of patent application of one of the joint inventors hereof, Serial No. 617,719, filed October 23, 1956, which is a continuation-in-part of Serial No. 306,845, filed August 26, 1952, now abandoned, and which gives some improved results over the use of Teflon alone.

One of the object of this invention is to further improve upon the composition of matter of two materials, which is the subject of the last application above mentioned.

A more specific object of the invention is to provide a composition which will better withstand wear in an unlubricated bearing which is subjected to pressure loads.'

Another object of the invention is to reduce the coeflicient of friction of an unlubricated bearing material which is subjected to loads.

Polytetrafluoroethylene when molded into the form desired has a very smooth and slippery or greasy feel to the hand and provides an excellent low co-eificient of friction. When used alone, however, it has very low wear resistance to abrasion and willl not stand up as a hearing under load, such for instance as the weighting of a top roll for a spinning frame. Glass particles such as fibers or powders are usually considered abrasive and are not often thought of in connection with use in a bearing. However, we have discovered that by placing small particles of glass of other silicate such as mica, aluminum silicate or tale in polytetrafluoroethylenc the resistance to abrasion is increased and further found that it, together with any one of the selected silicates, small particles of some metal or metal oxides are used with polytetrafluoroethylene (Teflon) and dispersed through the Teflon, the resistance to abrasion is further materially increased, the co-elficient of friction is reduced, and the bearing will stand up under pressures developed in its use as the top rail bearing for a spinning frame or for other uses where pressure on the bearing is used. The metal or metal oxide is used in place of a part of the silicate rather than being substituted for Teflon. Generally speaking, the polytetrafluoroethyelne is present by volume in from 50 percent to percent with a preferred smaller range of from 65-75 percent with the remainder of the material having substantially one part of metal or metal oxides to two parts of a silicate such as glass, talc, aluminum silicate, or mica, ranging to equal parts of the metal or metal oxide and silicate.

The silicates, glass, talc, aluminum silicate, and mica, are not equivalents but each when used with polytetrafluoroethylene is improved when a metal or metal oxide is used with the particular silicate selected to be incorporated in the polytetrafiuoroethylene rather than the use of the two materials of Teflon and silicate.

The glass is usually in the form of glass fibers milled about y of an inch long, or they may be ground glass or in the form of spheres or beads. The glass fibers are prepared by burning olf any lubricant or resin on the fibers, which requires heating the glass fibers to about 600 F. The metal or metal oxides are prepared by grinding or pulverizin g a metal or its oxides and thoroughly cleaning the same.

The mica is wet ground to 500 mesh. The mic is in the grade which may be purchased on the market as "Lo Micron" and the aluminum silicate is used in a grade which may be purchased on the market as Fiberfrax-Grade S, from Carborundum Company.

The selected quantity of Teflon with parts of pulverized silicate material and pulverized metal or metal oxide are mixed together at room temperature and tumbled to get a fairly uniform mixture. This mixture then goes into a pulverizing machine to grind and further mix the Teflon, silicate, and metal or metal oxide. An alternate method is to add the silicate and metal or metal oxide to an aqueous suspension of the Teflon and disperse them by agitation. The solids may then be precipitated by the addition of a non-aqueous solvent such as acetone, while stirring. The uniform mixture obtained is filtered, washed and dried at about 200 F., providing a puttylike homogeneous material suitable for molding.

The material formed by either of the above methods is placed in the top of an extrusion die. An air-operated ram forces a charge of the powder down into the die or mold. This ram operation is repeated. The charge reaches an externally heated portion of the mold and is there sintered at about 700? F; After passing the heated portion of the mold, the material is cooled enough by a draft of air to shrink it to the desired size and shape. It has been found that Teflon charged with the silicate and metal or metal oxide does not shrink nearly as much as Teflon alone. After shrinkage is complete, the rod-like material is forced out of the die or mold and cut into the proper lengths. The above is where a number of bearings are continuously formed in rod-like fashion and then cut-off, but powder may be placed in a mold shaped for a single bearing. The mold must be of a size larger than the finished size in order that shrinkage may be allowed for. A pressure of 2,000 pounds per square inch or more is put on the powder to make it cling together in the form of a bearing. The powder thus formed may then be placed on a pan and be put into an oven where the material is heated up to about 700 F. To heat the material for a bearing of the size about /2" x /2.", the heat will be continued for about an hour until the sub stance becomes translucent. It is possible to take the hot bearings from the oven and force them into different mltl\ of the correct size and then chill them all quickly. This will produce the proper size uniformly solid bearing, and thc coefficient of friction will be lowered.

the following tests were run on pellets A; x x Va than if the same percentage of Teflon is used with a silicute and a metal or metal oxide. From the examples also it will be noted that the silicate and metal oxide may be in equal percentages by volume or the silicate may be in substantially twice the volume as the metal inch on 1 inch water cooled shaft at 425 r.p.m. with a. 5 or metal oxide, and in each one of these situations, the loud of 2.9 pounds. Pellets were made by mixing Teflon 'leflon with the two ingredients, that is, a silicate and and fillers [11 a MieroPulverizer, pressing in a mold and metal or metal oxide, superior in resistance to wear than sintcring. Data below represent the average weight loss either the Teflon used with jLlSll the silicate or ust the for duplicate pellets after 72 hours. Filler percentages metal or metal mode. are reported by volume percent. 10 Thus, it will be noted in Table I that item 1 would be Table No. 1

Item Percent Percent. Metal tvrt-rnt No. Teflon Percent Silicate l'crwnt Metal (hide lin -tit ANN l 70 3t] filasmunu. c c 1.t a l. 2 70 all lt'tL. 1.4 A a 7n 3 lTitlC.. an

7 7a Lead 20.7 tiroiit) "ll" 8 7t] r 30 Ht! lio'itL 7 H. i

10 70 r 3 1 Almuinul H. 1K 5 12 7D 1] Column... i5

H 70 11 Lead .3

i5 70 )1 Red Lea 'L l 16 TU 11 Copper Oxide w 18 7t) 11 Altuninum h 1.7

19 T 11 Coptic-n.7 r. 1.5

20 7t) 11 Molybdenum, .3

21 70 11 Lead. is

22 T0 ll Red Lead. Ma

23 70 11 Copper ()virltg 2 .2

24 7o t-t w "I l 5 ttroup L3 29 70 c. It ttett LWL 3.5

32 70 More... 2.1%

33 70 19 Fibe fax ll toppcr. 7.1!

34 To ,do t1 Molybdenum .57

36 70 ,do 11 Red Lead L4 37 7t] do 11 Copper Oxide" 4. 4

as m .tlo 2:4

39 Ill H1101 ll Silvana" U 2 1 Vim-rims is the trade name for aluminum silicate. I These wort so badly that they hurl to he removed before 72 hours. 11cm 8 run .It hours; lteui i) ran 51mins.

Table No. 2

l'trtlllt Percent. Percent Metal lcrccnt TtllULl Silicate Percent Metal Uxidc Whi -lit Loss . s 7 c .7 1. R

c c c c 2a ltcd Lcutl. 0. it? .UlylltlCltllitL s 0. i l .25 Red Load. 0.57 25 hlUlylltlCItUltL (t. tit 25 Silvcr 0.3 do 1.5 1.5 4, 4 7. 2 4. ll

. Lt 20 Red Lead .3

. .ll ll) Red Lt*tt(l .4

H .7 1.7 10] lLtu L. 3.4

It] to||p r v 2. (1 1t) Lcu l .7 1.5 l0 Rltl Lear], 4J3

l, 7 10 Silver" Ll tlo 1.5 c., lt r 0.8

From the above tables, it will be apparent that the use of a selected percentage of Teflon within the range of St) to 80% above set forth and one other material either a silicate, metal, or metal oxide has a much greater wear [tern 6 ran 24 hours; Item 7 ran 7 hours.

comparable with items 12 to 18, while item 2 would be comparable with items I) to 25, item 3 would be comparable with items 26 to 32 and item 4 would be comparable with items 33 to 39.

We claim:

1. A bearing for a relatively moving surface consisting essentially of a homogeneous mixture of the three components polytetrafluorocthylene present by volume of 50% to a silicate selected from the group consisting of glass, tale, mica and aluminum silicate and a third material selected from the group consisting of aluminum, molybdenum, silver, copper. lead, lead oxide and copper oxide, the silicate being present by volume in from equal parts to twice the third material, whereby the presence of the third material imparts increased wear resistance as compared with a two part mixture of polytetrafiuoroethylcne wherein the silicate or third material would be present in amount equal to the sum of the silicate and the third material in the three part mixture.

2. A bearing for a relatively moving surface consisting essentially of a homogeneous mixture of the three compo nents polytetrat'iuorocthylcne present by volume of 50% to 80%. glass and a third material selected from the group consisting of aluminum, molybdenum, silver, copper, lead, lead oxide and copper oxide, the glass being present by volume in from equal parts to twice the third material, whereby the presence of the third material imparts increased wcar resistance as compared with a two part mixtrue of polytetrafluoroethylene wherein the glass or third material would be present in amount equal to the sum of the glass and the third material in the three part mixture.

3. A bearing for a relatively moving surface consisting essentially of a homogeneous mixture of the three components polytetrafiuoroethylene present by volume of 50% to 80%, talc and a third material selected from the group consisting of aluminum, molybdenum, silver, copper, lead, lead oxide and copper oxide, the tale being present by volume in from equal parts to twice the third material, whereby the presence of the third material imparts increased wear resistance as compared with a two part mixture of polytetrafluoroethylene wherein the tale or the third material would be present in amount equal to the sum of the tale and the third material in the three part mixture.

4. A hearing for a relatively moving surface consisting essentially of a homogeneous mixture of the three components polytetrafiuoroethylene present by volume of 50% to 80%, mica and a third material selected from the group consisting of aluminum, molybdenum, silver, copper, lead, lead oxide and copper oxide, the mica being present by volume in from equal parts to twice the third material, whereby the presence of the third material imparts increased wear resistance as compared with a two part mixture of polytetrafluoroethylene wherein the mica or the third material would be present in amount equal to the sum of the mica and the third material in the three part mixture.

5. A bearing for a relatively moving surface consisting essentially of a homogeneous mixture of the three components polytetrafiuoroethylene present by volume of 50% to 80%, aluminum silicate and a third material selected from the group consisting of aluminum, molybdenum, silver, copper, lead, lead oxide and copper oxide, the aluminum silicate being present by volume in from equal parts to twice the third material, whereby the presence of the third material imparts increased wear resistance as compared with a two part mixture of polytetrafluoroethylene wherein the aluminum silicate or the third material would be present in amount equal to the sum of the aluminum silicate and the third material in the three part mixture.

6. A hearing as in claim 1 wherein polytetraiiuoroethylene is present by volume in a range of 65-75%.

7. A bearing as in claim 2 wherein polytetrafluoroethylene is present by volume in a range of 66-75%.

8. A bearing as in claim 3 wherein polytetrafluoroethylene is present by volume in a range of 6575%.

9. A hearing as in claim 4 wherein polytetrafluoroethylene is present by volume in a range of 6575%.

10. A bearing as in claim 5 wherein polytetrafluoroethylene is present by volume in a range of 6S-75%.

11. A hearing as in claim 1 wherein polytetrafluoroethylene is present in 70% by volume.

12. A hearing as in claim 1 wherein polytetrafiuoroethylene is present in 70% by volume and the silicate is present by volume in 19% and the third material is present by volume in 11% whereby the presence of the third material imparts increased wear resistance as compared with a two part mixture of polytetrafluoroethylene wherein the silica or the third material would be present in amount equal to the sum of the silicate and third material in the three part mixture.

13. A hearing as in claim 12 wherein the silicate is glass.

14. A bearing as in claim 12 wherein the silicate is talc.

15. A bearing as in claim 12 wherein the silicate is mica.

16. A bearing as in claim 12 wherein the silicate is aluminum silicate.

17. A hearing as in claim 12 wherein the third material is lead.

18. A bearing as in claim 12 wherein the third material is lead oxide.

19. A bearing as in claim 12 wherein the third material is aluminum.

20. A bearing as in claim 12 wherein the third material is molybdenum.

21. A hearing as in claim 12 wherein the third material is silver.

22. A bearing as in claim 12 wherein the third material is copper.

23. A bearing as in claim 12 wherein the third material is copper oxide.

24. A composition of matter consisting essentially of a homogeneous mixture of the three components polyteirufluorocrhylene present by volume of 50% to a silicate selected from the group consisting of glass, talc, mica and aluminum silicate and a third material .Sclcclcd from the group consisting of aluminum, molybdenum, silver, copper, lead, lead oxide and copper oxide, the .rilicate being present by volume in from equal parts to twice the third material, whereby the presence of the third maierial imparts increased wear resistance as compared with a two part mixture of polyrctrafluoroclhylene wherein the silicate or third material would be present in amount equal to the sum of the silicate and the third material in the three part mixture.

25. A composition of marter consisting essentially of a homogeneous mixture of the three com poncnls polytczrafluoroerhylene present by volume of 50% 1o 80%, glass and a third material selected from the group consisting of aluminum, molybdenum, silver, copper, lead, lead oxide and copper oxide, the glass being present by volnmc in from equal parts to twice the third material, whereby the presence of the third material imparts increased wcnr rcsistance as compared with a two part mirlure of poly- Ietrafluoroeihylcnc wherein the glass or third nuncrinl would be present in amount equal to the sum of the glass and the third material in the three part mixture.

26. A composition of mailer consisting essentially of a homogeneous mixture of the thrcc ((JflljJUlltlllS Polvicirm fluoroethylene present by volume of 50% to 80%, talc and a third material selected from the group consisting of aluminum, molybdenum, silver, copper, lead, lead oxide and copper oxide, the talc being present by volume in from equal parts to twice the third material, whcrcl y the presence of the third material imparts increased wcrrr resistance as compared with a two part mixture of poly- Ierrafluoroethylene wherein the talc or the third nmtcrinl would be present in amount equal to the sum of the talc and the third material in the three part-mixture.

27. A composition of mailer consisting mscnriully of a homogeneous mixture of the three components polyicrrafluorocrhylcne present by volume of 50% to 80%, mica and a third material sclcclcd from the group consisting of aluminum, molybdenum, silver, copper, lcad, lend oxidc and copper oxide, the mica being prcscnl by volume in from equal parts to twice the third muicriril, whcrcby the presence of the third material imparts incrcnscd wcur rcsisrance as compared with a two port mixiurc of polylcrrufluoroethylcne wherein the mica or the third murcriul would be present in amount equal to the sum of the mica and the third malarial in the three part mixture.

28. A composition of mailer consisting csscnliully of a homogeneous mixture of the Ihrce componcnts polyteirafluoroelhylene present by volume of 50% to 80%, aluminum silicate and a third material selected from tho group consisting of aluminum, molybdenum, silver, copper, lead, lead oxide and copper oxide, the aluminum .llllcare being present by volume in from equal parts lo twice the third material, whereby the presence of the third ma- Ierial imparts increased wear resistance as compared with a two part mixture of polyictrafluorocthcylcne whcrcin the aluminum silicate or the third malcriol would be prvsent in amount equal to the sum of the aluminum silicate and the third material in the three part mixture.

29. A composition of mailer as in claim 24 n-hcrcin 7 olytctinflnorocthylene is present by volume in H, m rscz.

it]. A composition of matter as in claim 25 olvtctrofinoroethylene is present by volume in 31. A composition of matter as in claim 26 ,rn lstetrollnoroethylene is present by volume in of 65-75%.

32. A composition of matter as in claim 27 polytetrafltioroethylene is present by volume in of 654.5%. t

33. A composition of matter as in claim 2 wherein polytetrafluoroethylene is present by volume in a range of 65-75%.

34. A composition of matter as in claim 24 wherein polytetrafinoroethylene is present in 70% by volume.

35. A composition of matter as in claim 24 wherein pol \'tetraflnoroetltylene is present in 70% by volume and the silicate is present by volume in 19% and the third matcriol is present by volume in 11% whereby the presence of the third material imparts increased wear resistance as compared with a two part mixture of polytetrafluoroethylene wherein the silicate or the third material would be present in amount equal to the sum of the silicate and third material in the three part mixture.

36. A composition of matter as in claim 35 wherein the slllteile' is glass.

37. A composition of matter as in claim 35 wherein the silicate is talc.

38. A composition of matter as in claim 35 wherein the silicate is mica.

39. A composition of matter as in claim 35 wherein the silicate is aluminum silicate.

a range wherein a range wherein a range wherein a range 40. A composition of matter as in claim wherein the third material is lead.

4]. A composition of matter as in claim 35 wherein the third material is lead oxide.

42. A composition of matter as in claim 35 wherein the third material is aluminum.

43. A composition of matter as in claim 35 wherein the third material is molybdenum.

44. A composition of matter as in claim 35 wherein the third material is silver.

45. A composition of matter as in claim 35 wherein the third material is copper.

46. A composition of matter as in claim 35 wherein the third material is copper oxide.

References Cited by the Examiner The following references. cited by the Examiner, are of record in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2,400,091 5/1946 Alfthan 264- 2,400,099 5/1946 Brubaker et al. 264127 2,685,707 8/1954 Llewellyn et a1. 26474 2,691,814 10/1954 Tait 29-1825 2,715,617 8/1955 White 26041 2,824,060 2/1958 White 25212.2

FOREIGN PATENTS 961,671 6/1964 Great Britain. 961,672 6/1964 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

I. VAUGHN, Assistant Examiner. 

